The FENIKS Survey: Stellar-Halo Mass Relationship of Central and Satellite Galaxies in UDS and COSMOS at 0.2 < z < 4.5

TL;DR

This study maps the relationship between stellar mass and halo mass of galaxies across a wide redshift range, revealing how star formation efficiency evolves with cosmic time using a novel HOD fitting method.

Contribution

Introduces a new smooth-z HOD fitting approach that improves constraints on the stellar-halo mass relationship at high redshift, accounting for cosmic variance effects.

Findings

Halo mass with peak star formation efficiency remains constant over redshift.

COSMOS+UDS data reduces cosmic variance, affecting halo mass estimates.

Star formation efficiency evolves with redshift along halo merger trees.

Abstract

We present a comprehensive analysis of the observed Stellar-to-Halo mass relationship (SHMR) spanning redshifts from 0.2 to 4.5. This was enabled through galaxy clustering and abundance measurements from two large (effective area ~ 1.61 deg^2) and homogeneously prepared photometric catalogs - UltraVISTA ultra-deep stripes DR3 (COSMOS) and FENIKS v1 (UDS). To translate these measurements into the SHMR, we introduce a novel halo occupation distribution (HOD) fitting approach (``smooth-$z$'') whereby HOD parameters between neighboring z-bins are connected via physically motivated continuity (smoothing) priors. As a result, the high constraining power at z <~ 2, due to a much wider dynamical range in stellar mass (~ 3 dex), helps constrain the SHMR at z >~ 2, where that range shrinks down to <~ 1 dex. We find that the halo mass is tightly coupled to star formation: the halo mass with peak integrated star-forming efficiency (SFE), M_h^peak remains constant within ~ 10^12.2 - 10^12.4 Msolar throughout the redshifts probed. Furthermore, we show that if we had relied on COSMOS alone (as opposed to COSMOS+UDS), as has been done by many preceding studies, M_h^peak would be systematically lower by up to ~0.15 dex at z < 1.5, highlighting the importance of mitigating cosmic variance. Finally, for the first time, we show how the SFE evolves with redshift as halos grow in mass along their progenitor merger trees, instead of at fixed halo masses.